This study evaluated the effect of strength training on the stretch-shortening cycle of muscle performance during countermovement jumping in untrained men (N = 8). Ss performed progressive heavy-resistance strength training twice a week for 12 weeks. Training loads ranged from 6-10 RM with the first four weeks ranging 12-16 RM. Training exercises were squat, hack squat, incline leg pres, isolated knee extension, hamstring curls and calf raises. All training exercises were performed as slow stretch-shortening cycles. Countermovement jumps were performed with hands on the hips on a force platform.

Maximal countermovement jump height increased 15% with training. Peak and mean power exerted during the concentric phase of the countermovement jump increased by 12 % and 19 %, respectively. Downward peak velocity increased 26% and the deceleration phase was shortened by 17%.